Abstract

Some features of small potassium clusters Kn, n ≦ 8 are investigated in a crossed laser-molecular beams experiment coupled with a time-of-flight mass spectrometer. Abrupt step is found in the mass spectrum for n = 8 when the ionizing wavelength is higher than the ionization potentials. Isotopic composition of each mass is observed. Different behavior in ionization potential spectral profiles between odd- and even-numbered clusters is shown. These effects are interpreted in terms of cluster formation and structures.